COMING UP:Saturday: At Chase Field, 5:10 p.m. Diamondbacks LHP Wade Miley (2-0, 2.77) vs. Rockies LHP Jeff Francis (1-2, 8.44).Sunday: At Chase Field, 1:10 p.m. Diamondbacks LHP Pat Corbin (2-0, 1.71) vs. Rockies RHP Jon Garland (2-1, 4.68).Monday: At Chase Field, 6:40 p.m., Diamondbacks RHP Ian Kennedy (1-2, 4.70) vs. Giants RHP Matt Cain (0-2, 6.59).Notable: Brandon McCarthy will be making his second consecutive start against the Rockies. The last time against Colorado, he gave up four earned runs in six innings and got a no decision. McCarthy is winless in his past five starts dating to 2012, and is 0-3 with a 7.11 ERA in that span. … Nicasio has made four appearances against the Diamondbacks and has yet to receive a decision. Nicasio has made three starts against Arizona, but tonight will mark his first at Chase Field.

By Nick Piecoro azcentral sportsThu Apr 25, 2013 11:56 PM

Scouting for the Angels four years ago, Tom Kotchman remembers seeing a left-hander at a Florida junior college named Pat Corbin sitting in the 88-89 mph range and touching the low-90s with his fastball.

Corbin exhibited many of the things scouts like to see out of young pitchers — he was wiry and athletic, with a loose arm and a clean delivery — but looking back on it, Kotchman says he never envisioned Corbin throwing as hard as he has at times this season.

“If I told you I saw 94-95, my nose would be growing like Pinocchio right now,” Kotchman said.

When it comes to getting outs, good velocity isn’t everything, but it certainly helps. So it figures that the harder a young pitcher throws, the better his chances of being a top pick in baseball’s amateur draft.

But then there are guys like Corbin, the ones who add a few extra ticks to their fastballs as they develop. Where does the added velocity come from? Is it predictable? And how often are scouts right when they say a pitcher is “projectable” and will eventually throw harder?

The answers depend on the scout you ask, but most seem to acknowledge that projecting velocity is not unlike most of the rest of their industry: There are rules of thumb to guide the process, but it’s ultimately an exercise rooted in unpredictability.

“If you’re talking about a high school kid,” said Bob Gebhard, a vice president and special assistant with the Diamondbacks, “you kind of want to see what their parents look like.”

It comes down to whether a scout thinks there’s room for growth, preferably in the form of a tall, broad-shouldered body that could add weight, according to baseball analyst Keith Law.

“We look for the guy who couldn’t walk over the storm drain because he might slip through the bars,” said Law, who has been scouting draft-eligible amateurs for ESPN since 2006.

Diamondbacks prospect Tyler Skaggs is a perfect example of this: Since being drafted out of high school in 2009, he’s added about 35 pounds to his 6-foot-5 frame, and in the process his fastball has gone from the upper-80s to the lower-to-mid-90s.

Then there’s the question of whether a little coaching might go a long way.

“You look to his delivery,” Gebhard said. “Is it something that, in your opinion, if you clean up the delivery or smooth it out, get him a little quicker, will the velocity increase? You want to see what kind of mechanics he has, keeping in mind that many times, especially high school kids, they’ve had nobody coaching them.”

Being realistic

Dozens of players in every draft might possess several or all of the attributes scouts look for but never throw harder. When asked how often his scouts are right in predicting velocity, Tampa Bay Rays scouting director R.J. Harrison laughed.

“Probably not nearly as often as we predict that they’ll throw harder,” he said. “I’ve tried to have that conversation with our guys. It’s a fine line; you don’t want your scouts to get gun shy. On the amateur side, you have to scout with the cup half-full, but you also have to be realistic.”

The way Houston Astros General Manager Jeff Luhnow sees things, to be realistic is to almost never expect a pitcher to throw harder.

“My rule of thumb is you can never project an increase in velocity because you’re going to be wrong a lot,” said Luhnow, formerly the scouting director for the St. Louis Cardinals. He makes an exception for certain prospects from Latin America who fairly predictably can go from the mid-80s at ages 14 or 15 to the low-90s.

Luhnow said his club has analyzed various factors to determine whether velocity jumps might be predictable and said there’s little to go by that “would suggest you can figure it out going forward.” Much more often, he said, a pitcher will wind up losing miles an hour on his fastball once he goes through the rigors of pro ball.

“There may be some scouts out there who have a formula that works for them, and they’ve had more success than I’ve had,” Luhnow said. “If there is, I’d love to hire him.”

Keep ’em healthy

Most conversations about projecting velocity tend to lead to questions about baseball’s biggest challenge: preventing pitcher injuries. For the Cardinals, the questions are intertwined.

“We look at it through a lens of durability, you could say,” Cardinals scouting director Dan Kantrovitz said. “We have some proprietary measures and indicators of a pitcher’s mechanics that we focus on and make extensive use of video analysis to do that. We try to isolate, say, the probability of this pitcher breaking down or staying healthy, and what I talk about a lot with our scouts is, you can’t add velocity to your fastball if you’re not healthy.”

Kantrovitz said they assign numerical grades — “more or less a probability” — on a pitcher’s likelihood of staying healthy. “Some people call these things a tiebreaker; it’s not really that for us,” he said. “It’s more a part of the equation.

“Nobody in our organization will tell you that our way is the only way. We definitely believe in it, put a lot of stock in it and certainly for our draft, I think over the years we’ve grown more confident in it. That’s maybe a sign of something that works.”

Diamondbacks scouting director Ray Montgomery said his job is an “inexact science.”

“I think they’re all going to get hurt at some point,” he said. “I see it as, who’s the better athlete and who’s going to come back from it? Who will be able to overcome it?”

So far, Corbin has been able to stay healthy, and he was a good athlete in high school. More of a basketball player when he was younger, he was a late bloomer in baseball, someone who had never really pitched prior to his junior year of high school. And while he’s not sure why he’s regularly hitting 93-94 mph early in his starts, he figures it’s probably just a matter of getting stronger as he grows.

Of course, there were things to like about Corbin before he added the velocity, which is what the scouts are also looking for before pulling the trigger on drafting or acquiring a young prospect.

“You don’t want to invest a ton of money in a kid where you’re hoping for velocity,” Harrison said. “Even though he may look good and it’s a young kid with a good frame and all that stuff, you can only pay so much for something you haven’t seen.”

Telling stats

National League leaders with Diamondbacks in bold. Statistics through Wednesday’s games.

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